The invention relates to an exhaust gas manifold of an exhaust system for an internal combustion engine.
EP 0 806 598 A1 discloses an exhaust gas manifold with exhaust pipes, which are connected together two-dimensionally in the adjoined area and otherwise diverge at an angle and do not lie unidirectionally next to one other. Furthermore, U.S. Pat. No. 6,122,911 discloses an exhaust gas manifold, where the exhaust pipes are joined to form a circular segment. The pipes form quadrantal segments, and the walls of these quadrantal segments lie next to each other only at the angular sides and otherwise have a gap in relation to each other.
An object of the invention is to create an improved exhaust gas manifold for an exhaust system of an internal combustion engine, in which the noises, such as the rattling noises, are avoided.
The invention solves this problem with the invention as described and claimed hereinafter.
One of the advantages of the invention is that a noise reduction can be achieved by separating the exhaust pipes from each other, preferably as far as possible, especially when they lie relatively close to each other and are arranged unidirectionally. To this end, the exhaust pipes are arranged unidirectionally in the pipe elbow, and the ends of the pipes form a circular cross section. The free ends of the exhaust pipes are connected together by a defined contact surface, which runs on the peripheral edge. The unidirectional exhaust pipes are separated by a gap. By attaching the exhaust pipes in the pipe elbow and in the fastening flange and by spacing the exhaust pipes between these attachments, rattling noises are reduced or eliminated.
To avoid the noises, the invention provides that the free ends of the exhaust pipes, which empty into the pipe elbow, include quadrantal segments each having a generally triangular configuration. Each pipe end has a relatively narrow edge, which projects outwardly with respect to the rest of the exhaust pipes, thus resulting in a gap between the exhaust pipes. The goal is achieved that the exhaust pipes lie side by side over a relatively small area (also defined at different temperatures) only at the edge of the pipe, and the pipes are separated from each other slightly by a gap. The edges of the pipes that lie side by side are either designed flat or has mating beads.
To avoid sympathetic vibrations in the pipe elbow, the pipe elbow has an internal pipe elbow, which is spaced apart from the external pipe of the pipe elbow and in which the edges of the free ends of the exhaust pipes are recessed. Between the external and internal pipes of the pipe elbow there is a ring or a wire mesh ring in the area of the edge. This design of the pipe elbow and of the free ends of the exhaust pipes significantly reduces the generation of noises, because the pipes do not directly contact the external pipe of the pipe elbow. The edge on the free end of the exhaust pipes has a direct connection to the external pipe by the pipe mesh ring.
The exhaust pipes are arranged so as to lie freely with a spacing gap and in particular in such a manner that the exhaust pipes, held by a fastening flange on the engine side, are connected in the exhaust gas manifold housing by a sliding connection to the continuing exhaust pipes and that the exhaust pipes are arranged so as to lie freely over the edge from the fastening flange up to the uptake in the pipe elbow. The sliding connection between the exhaust pipes in the housing of the exhaust gas manifold accommodates thermal expansion, and any vibrations of the exhaust pipes are reduced due to the friction between the connected pipes.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.